Erin Andrews' own detective work was integral in helping investigators track and arrest her suspected stalker, Andrews' attorney said today.

With the help of her stylist, Andrews, the ESPN reporter who was secretly filmed in the nude in her hotel room on multiple occasions, was able to identify the "exact room, the exact date and the exact location" where one of the videos was made, based on her blue jeans visible in the video, attorney Marshall Grossman told "Good Morning America" in an exclusive interview.

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"I've since learned that women know what they wear on [any] occasion," Grossman said with a smile.

That detailed information helped investigators identify Michael David Barrett, a 47-year-old divorced father, as the alleged stalker, based on hotel records.

Andrews' direct involvement in the case may be only the beginning, because she is "hellbent" on testifying against Barrett and will be working with authorities and lawmakers to toughen stalking laws, Grossman said.

"Originally, Erin was quite relieved with news of the arrest," he said.

But after Andrews reviewed investigators' reports and the enormity of the alleged crime was revealed, Grossman said, her anxiety has increased.

Barrett is expected in court today for a transfer hearing after his arrest Friday at Chicago's O'Hare International Airport.

Barrett's Neighbors 'Shocked' By Arrest

Investigators said they had been tracking Barrett for some time and that the divorced father stalked Andrews in Milwaukee and Nashville, Tenn., calling numerous hotels to learn her whereabouts and requesting rooms next to hers. The charges specifically allege that the Chicago-area man stalked Andrews "with the intent to harass and intimidate."

Andrews told Oprah Winfrey last month that when she saw the video, she thought it would spell the end of her career, screaming, "I'm done. My career is over. Get it off. ... Get if off the Internet." She has since returned to the sidelines for ESPN.

Barrett's attorney and longtime acquaintance Richard Beuke said he "is a great friend."

"I've gotten calls from 30 of his friends in the last 10 hours, all willing to give their support to him," Beuke told "Good Morning America" Sunday.

Barrett has no history of serious crime and seemingly had a successful career in sales.

Making secret videos or pictures of people can be all about power, according to ABC News consultant and former FBI agent Brad Garrett.

"The whole idea is that you can capture a photograph, and with that control somebody's life, is very powerful for him because people who are stalkers tend to feel powerless," Garrett told "Good Morning America."

Erin Andrews Case Moves Forward<

In a court hearing today, a judge will decide whether Barrett will be transferred to Los Angeles, where the FBI filed the stalking charges. If convicted, Barrett faces up to five years in prison.

Beyond Barrett, Grossman did not say whether Andrews would pursue legal action against the hotels, despite the reports that Barrett often called the hotels to find out where Andrews was.

Marriot International, which owns the Nashville hotel in which one of the videos was allegedly shot, released a statement saying that the company "takes it guests' security and privacy seriously and has been cooperating with investigators."

Ramada Worldwide, which owns the Radisson hotel in Milwaukee where another video was allegedly shot, said the safety and privacy of their guests was "of utmost importance" and that they are looking into the matter.